jdk1.5 锁 Lock 和 Condition

最新推荐文章于 2021-10-31 15:40:37 发布

原创最新推荐文章于 2021-10-31 15:40:37 发布 · 124 阅读

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#lock #condition

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本文通过两个示例深入探讨了Java中线程间的同步与通信机制：一是使用ReentrantLock实现不同线程对资源的安全访问；二是利用Condition实现线程间的等待与通知交互，确保父子线程能够按预期顺序交替打印。


// lock 练习
public class LockTest{


	public static void main(String[] args) {
		// TODO Auto-generated method stub
		new LockTest().init();
	}

	private void init(){
		final Outputer out=new Outputer();
		new Thread(
		new Runnable() {
			@Override
			public void run() {
				// TODO Auto-generated method stub
				while (true) {
					try {
						Thread.sleep(10);
					} catch (InterruptedException e) {
						// TODO Auto-generated catch block
						e.printStackTrace();
					}
					out.output4("English");
				}
			}
		}
		).start();

		new Thread(
			new Runnable() {
				@Override
				public void run() {
					// TODO Auto-generated method stub
					while (true) {
						try {
							Thread.sleep(10);
						} catch (InterruptedException e) {
							// TODO Auto-generated catch block
							e.printStackTrace();
						}
						out.output4("Chinese");
					}

				}
			}
		).start();

	}

	//使用各种 同步锁对象   this,.class ,Object ,Lock 
	static class Outputer{
		Lock lock=new ReentrantLock();
		public void output4(String name){
			int len=name.length();
			lock.lock();   //使用 jdk 1.5 提供的锁
			try {
				for (int i = 0; i < len; i++) {
					System.out.print(name.charAt(i));
				}
				System.out.println();
			} catch (Exception e) {
				// TODO: handle exception
			}finally{
				lock.unlock();
			}
		} 

	}

}

//condition



import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

/**
 *父子线程 交替打印10 次, 100次
 * @author Bin
 */
public class ConditionCommunication {
	static boolean isSubRun=true;
	/**
	 * @param args
	 */
	public static void main(String[] args) {
		/*new Thread(
			 new Runnable() {

				@Override
				public void run() {
					int num=0;
					synchronized (TraditionalThreadCommunication.class) {
						while (num<=4) {
							if(!isSubRun){
								try {
									TraditionalThreadCommunication.class.wait();
								} catch (InterruptedException e) {
									// TODO Auto-generated catch block
									e.printStackTrace();
								}
							}
							for (int i = 0; i < 10; i++) {
								System.out.println(Thread.currentThread().getName()+" run "+i);
							}
							isSubRun=false;
							TraditionalThreadCommunication.class.notify();
							num++;
						}
					}
				}
			}
		).start();

		new Thread(
				new Runnable(){
					@Override
					public void run() {
						int num=0;
						while(num<=4){
							synchronized (TraditionalThreadCommunication.class) {
								if(isSubRun){
									try {
										TraditionalThreadCommunication.class.wait();
									} catch (InterruptedException e) {
										// TODO Auto-generated catch block
										e.printStackTrace();
									}
								}
								for (int i = 0; i < 100; i++) {
									System.out.println(Thread.currentThread().getName()+" run "+i);
								}

								isSubRun=true;
								TraditionalThreadCommunication.class.notify();
								num++;
							}

						}
					}

				}

		).start();*/

		final Business bus=new ConditionCommunication().new Business();
		new Thread(){
			@Override
			public void run() {
				for (int i = 1; i < 5; i++) {
					bus.sub(i);
				}
			}
		}.start();

		new Thread(new Runnable(){
			@Override
			public void run() {
				for (int i = 1; i < 5; i++) {
					bus.main(i);
				}
			}
		}).start();

	}

	class Business{
		Lock lock=new ReentrantLock();
		Condition condition=lock.newCondition();
		private boolean sShouldSub=true;
		public void sub(int i){  //synchronzied  有 lock 替代
			lock.lock();
			try {
				if(!sShouldSub){  //这里换成  while
					try {
						//this.wait();
						condition.await();
					} catch (Exception e) {
						// TODO Auto-generated catch block
						e.printStackTrace();
					}
				}
				for (int j = 1; j <= 10; j++) {
					System.out.println("Sub thread sequence of "+j+" loop of"+i);
				}
				sShouldSub=false;
				//this.notify();
				condition.signal();  
			} finally{
				lock.unlock();
			}

		}

		public void main(int i){
			lock.lock();
			try {
				while(sShouldSub){//这里换成while 比 if 更 安全 健壮 
					try {
						//this.wait();
						condition.await();
					} catch (InterruptedException e) {
						// TODO Auto-generated catch block
						e.printStackTrace();
					}
				}

				for (int j = 0; j < 100; j++) {
					System.out.println("Main thread sequence of "+j+" loop of"+i);
				}
				sShouldSub=true;
				//this.notify();
				condition.signal();
			} finally{
				lock.unlock();
			}

		}

	}

}